Showing papers on "Landing gear published in 1979"

Landing gear energy distribution and righting system

Abstract: Each landing gear of the undercarriage of an aircraft includes an hydraulic cylinder, and the hydraulic cylinders are interconnected through hydraulic restoring devices. The hydraulic restoring devices yieldably urge the pistons in each of the hydraulic cylinders to an equilibrium position, thereby restoring the length of each landing gear to an equilibrium length following a disturbance. In non-level landings, the hydraulically interconnected system causes the landing gear that strikes the ground first to be compressed and the other landing gears to be extended; this absorbs some of the energy of the impact. Extension of the other landing gears tends to limit the extent to which landing energy is converted to angular velocity of the aircraft caused by pivoting of the center of gravity of the aircraft about the first landing gear to contact the ground. Once all of the landing gears have contacted the ground, the restoring device acts to restore the aircraft to its normal equilibrium attitude with respect to the ground. In the event a non-level landing is aborted after one of the landing gears has struck the ground, the restoring device restores the landing gears to their normal in-flight configuration with respect to the airframe as the aircraft becomes airborne again in preparation for the next landing attempt.

Adaptive airplane landing gear

Abstract: A duo mode gas hydraulic shock absorbing landing gear strut with a pneumatic spring in combination with a hydraulic fluid controlling orifice for touchdown and automatic means for changing mode after touchdown to impart new pneumatic spring characteristics and to provide duo paths for controlling hydraulic fluid flow.

Kneeling nose landing gear assembly

Abstract: A kneeling nose landing gear assembly for an airplane enables the nose of the airplane fuselage to be lowered to facilitate loading and unloading of cargo. A pair of hydraulic kneeling actuators pivotally coupled to the midsection of a pivotable landing gear strut are selectively positionable against a pair of retractable stop assemblies positioned above the strut. The actuators are pressurized against the cooperable stop assemblies to thereby cushion the descent of the airplane nose to a lowered position wherein the landing gear strut is pivoted forwardly into an angled kneeling position intermediate between an upright taxiing position and a retracted position. The kneeling actuators are subsequently pressurized to raise the nose of the airplane and swing the landing gear strut back into the taxiing position from the kneeling position. The kneeling actuators and their associated elements for providing the kneeling capability of the landing gear may be retrofitted to existing nose landing gear assemblies with negligible modification of the landing gear and without interfering with normal retraction or extension of the landing gear.

Soft landing gear

Abstract: A bogie type landing gear especially suitable for providing soft landing capabilities for short take-off and landing (STOL) aircraft wherein fore and aft wheels are mounted on opposite ends of a bogie which is pivotally attached to the lower end of a vertical shock strut. In one embodiment, a torque link pivotally connects the aft end of the bogie to the shock strut such that, under normal landing conditions, the front wheel will touch down first thereby reducing and directing the landing forces to minimize shock to the aircraft. The aft mounted torque links also act as a tension member during the initial landing stroke. In another embodiment, a damper acts as a tension stop for a soft landing arrangement as well as to dampen bogie motion over bumps with the torque links being separate.

Behavior of aircraft antiskid braking systems on dry and wet runway surfaces. A slip-velocity-controlled, pressure-bias-modulated system

Abstract: The braking and cornering response of a slip velocity controlled, pressure bias modulated aircraft antiskid braking system is investigated. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC 9 series 10 airplane. The landing gear strut was replaced by a dynamometer. The parameters, which were varied, included the carriage speed, tire loading, yaw angle, tire tread condition, brake system operating pressure, and runway wetness conditions. The effects of each of these parameters on the behavior of the skid control system is presented. Comparisons between data obtained with the skid control system and data obtained from single cycle braking tests without antiskid protection are examined.

Analytical investigation of the landing dynamics of a large airplane with a load-control system in the main landing gear

Abstract: The results of an evaluation of an active load-control landing gear computer program (ACOLAG) for predicting the landing dynamics of airplanes with passive and active main gears are presented ACOLAG was used in an analytical investigation of the landing dynamics of a large airplane with both passive and active main gears It was concluded that the program is valid for predicting the landing dynamics of airplanes with both passive and active main gears It was shown that the active gear reduces airframe-gear forces and airplane motions following initial impact, and has the potential for significant reductions in structural fatigue damage relative to that which occurs with the passive gear

Inertia Calculation Procedure for Preliminary Design

Abstract: : This report explains the methods involved in estimating aircraft moments of inertia for preliminary design purposes Assumptions that were made for this procedure and the derivation of equations that evolved from these assumptions are included An example using the method on the C-5A aircraft is shown This procedure requires a knowledge of the major aircraft group weights, the location of major components (landing gear, avionics bay, etc), geometry information, and inertias of some major subsystem items Using this data, the moments of inertia about the roll, pitch, and yaw axes are calculated as well as the roll-yaw cross-product of inertia

Spherical living module or space

Abstract: A substantially spherical human living module or space has a plurality of pontoons projecting from its lower hemisphere. It is preferably arranged to be self-propelled, as a vehicle, and the pontoons are preferably extensible and retractable. In a version in which wheeled landing gear is provided, a spherical human living space is provided with helicopter blades and four jet engines at the bottom of the craft, and two jet engines on the right and left sides, which swivel for direction control, for propelling the device.

Hydraulic nose landing gear steering actuator for an airplane

Abstract: A hydraulic aircraft nose landing gear steering actuator includes a coaxial stator and rotor ring assembly mounted on the fixed outer cylinder of a nose landing gear shock absorber strut. Hydraulic vanes protruding radially inwardly and outwardly from the rotor and stator, respectively, form semi-annular pressure chambers between the stator and rotor rings which may be selectively hydraulically pressurized. A torsion link connects the steering actuator to the landing gear wheels. The steering actuator is capable of providing a constant steering torque to the landing wheels over a total steering displacement angle of approximately 150°.

Methods for loading an air transportable trailer aboard an aircraft and for unloading it therefrom

Abstract: Mobile, air transportable, trailers or vans which have retractable landing gear at one end thereof, a jacking/skid plate at the opposite end, and retractable running gear. The disclosed trailers can be loaded on and unloaded from aircraft without removing the underbody of the trailer and without ground handling equipment by as few as two persons.

Airframe noise measurements on a small-scale model of a supersonic transport concept in an anechoic flow facility

Abstract: Airframe noise has been measured on a .015 scale model of an advanced supersonic transport concept (AST-100) in an anechoic flow facility. The model was equipped with leading- and trailing-edge flaps, nose and main landing gears, and engine nacelles. Each of these components was deployed, individually and collectively, to determine their contribution to the noise field. Results are presented which show that in the clean configuration the aircraft displays a symmetric dipole directivity, whereas in the more complex landing-approach configuration the directivity peaks in the forward quadrant. It was found that the landing-approach noise was due chiefly to the landing gear, the trailing edge flaps, and the aeroacoustic interaction between the two

Testing and analysis of dual-mode adaptive landing gear, taxi mode test system for YF-12A

Abstract: The effectiveness of a dual mode adaptive landing gear system in reducing the dynamic response of an airplane during ground taxiing was studied. The dynamic taxi tests of the YF-12A research airplane are presented. A digital computer program which simulated the test conditions is discussed. The dual mode system as tested provides dynamic taxi response reductions of 25 percent at the cg and 30 to 45 percent at the cockpit.

An electric control for an electrohydraulic active control aircraft landing gear

Abstract: An electronic controller for an electrohydraulic active control aircraft landing gear was developed. Drop tests of a modified gear from a 2722 Kg (6000 lbm) class of airplane were conducted to illustrate controller performance. The results indicate that the active gear effects a force reduction, relative to that of the passive gear, from 9 to 31 percent depending on the aircraft sink speed and the static gear pressure.

Ram wing aircraft launch platform system

Abstract: A launch platform for conventional landing gear aircraft having the launch platform configured as a ram wing structure with wheel latches secured to the platform. The platform is secured to the aircraft by means of the wheel latches. The wheel latches are released to permit the aircraft to leave the platform by pilot command. A parachute system is provided for platform deceleration after aircraft take-off. Spoilers are provided on the ram wing for stabilization of the ram wing during rotation.

Air cushion landing gear applications study

Abstract: A series of air cushion landing gear (ACLG) applications was studied and potential benefits analyzed in order to identify the most attractive of these. The selected applications are new integrated designs (not retrofits) and employ a modified design approach with improved characteristics and performance. To aid the study, a survey of potential users was made. Applications were evaluated in the light of comments received. A technology scenario is developed, with discussion of problem areas, current technology level and future needs. Feasible development timetables are suggested. It is concluded that near-term development of small-size ACLG trunks, exploration of flight effects and braking are key items. The most attractive applications are amphibious with very large cargo aircraft and small general aviation having the greatest potential.